Pradhan S, Urwin N A, Jenkins G I, Adams R L
Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K.
Biochem J. 1999 Aug 1;341 ( Pt 3)(Pt 3):473-6.
The presence of two DNA methyltransferases in Pisum raises the possibility that they serve different functions. In vitro methylation of CWG sequences in the strong cauliflower mosaic virus 35S promoter had no effect on reporter gene expression. In contrast, in vitro methylation of CWG sequences in the relatively weak, CG-deficient Phaseolus vulgaris rbcS2 promoter inhibited transcription. Expression of both constructs was strongly inhibited by extensive CG methylation. A search of published plant promoter sequences revealed that the CG content of promoters is very variable, with some promoters having typical CG islands. In contrast, the distribution of CWG sequences is more even with little evidence for CWG islands.
豌豆中存在两种DNA甲基转移酶，这增加了它们具有不同功能的可能性。在强花椰菜花叶病毒35S启动子中对CWG序列进行体外甲基化对报告基因的表达没有影响。相反，在相对较弱、缺乏CG的菜豆rbcS2启动子中对CWG序列进行体外甲基化会抑制转录。两种构建体的表达都受到广泛的CG甲基化的强烈抑制。对已发表的植物启动子序列进行搜索发现，启动子的CG含量变化很大，一些启动子具有典型的CG岛。相比之下，CWG序列的分布更为均匀，几乎没有CWG岛的证据。
